Assessment of different persulfate activation methods for the degradation of organic contaminants in water : application to pharmaceutical compounds -

Abstract

The aim of this work was to assess the different persulfate (PS) activation techniques for the degradation of recalcitrant pharmaceutical contaminants. To achieve this aim, two selected pharmaceutical active ingredients (PAIs): Chloramphenicol (CAP) an antibiotic drug, and Ketoprofen (KTP) an anti-inflammatory drug were tested in different PS activated systems. The degradation of CAP was initially studied in UV-PS system using lab grade materials and equipment. The system was optimized by varying [PS]0, [CAP]0, and UV fluence to obtain the highest percent reaction stochiometric efficiency (RSE). Results showed that: Highest percent RSE achieved was 52percent at [PS]0 = 0.25 mM, [CAP]0 = 31 µM and UV fluence = 330 J after 1 h. These conditions were later adopted to study the effect of various organic additives such as humic acids (HAs) and fumaric acid (FA), and inorganic additives such as HCO3-, Cl-, SO42-, NO3-, NO2-, and HPO42- on the overall efficiency of the degradation process. The system’s performance was less affected in the case of inorganic additives while HAs and FA affected strongly the oxidation performance. The solution’s pH did not noticeably alter the percent CAP degradation. The performance of this system was also tested in natural water matrices (wastewater and river water) and the results showed that the oxidative reaction was more efficient in filtered samples compared to non-filtered samples. Finally, a degradation mechanism based on hydroxylation and sulfonation was proposed. The second part of this work was more comprehensive in terms of PS activation techniques. Ketoprofen (KTP), a common over the counter NSAID, has been detected in the environment around the world and thus is considered as a representative organic contaminant for the aforementioned class of drugs. KTP degradation has been studied under PS based Advanced Oxidation Process (AOP) activated thermally, chemically (Fe2+) or by UV. Several experimental parameters have been taken into consideration to achieve effective removal of KTP